Piston stroke adjustment



y 1964 ,w. KNOWLES 3,

PISTON STROKE ADJUSTMENT Original Filed Feb. 27, 1959 S Sheets-Sheet 1 INVENTOR.

July 28, 1964 v w. 1.. KNOWLES 3,142,185

PISTON STROKE ADJUSTMENT July 28, 1964 w. L. KNOWLES 3,142,185

PISTON STROKE ADJUSTMENT Original Filed Feb. 27, 1959 3 Sheets-Sheet 3 l lllllllll Mu/AM Z. .Kvan zzs Arron 5Y5;

United States Patent 3,142,185 PISTON STROKE ADJUSTMENT William L. Knowles, Dallas, Tex., assignor to T-Board Machinery Company, Inc., Dallas, Tex., a corporation of Texas Original application Feb. 27, 1959, Ser. No. 796,119. Divided and this application June 6, 1962, Ser. No.

3 Claims. 01. M45

This invention relates to a piston stroke adjustment mechanism.

A primary object of this invention is the provision of an improved means or varying the stroke of a piston. The invention has particular applicability to the type of apparatus disclosed in my co-pending application Serial No. 796,119, filed February 27, 1959, entitled Composition Board, Method and Apparatus for Forming the Same, now abandoned in favor of continuation-impart application Serial No. 226,766, filed September 14, 1962. This case is a division of parent application Serial No. 796,119. The invention has broader application and use in machines of types other than disclosed in said parent application.

A more particular object of the invention is the provision of a mechanism for varying the stroke of the piston of an apparatus without interruption or stopping the machine.

A more specific object of the invention resides in the provision of a mechanism whereby the stroke of a forming piston in an apparatus for forming composition board may be varied in length while forcing a mixture or composition of sawdust and resin binder between a pair of heated molds, the lower of which includes a series of vertical grooves so that the formed board is comprised of a plane surface having a plurality of flanges depending therefrom, but returning the piston to the same starting point regardless of the length of stroke.

The desirability of such a stroke variation in this particular apparatus and the reasons therefor are fully set forth in my above-mentioned co-pending application but may briefly be described as a means for compensating the difference in the coefficient of friction of higher density Woods or ligno-cellulose particles which may be admixed with similar particles of lower density of materials. The length of pressure applying mold surfaces through which the material forced is varied with the various types of material employed arid the variations of stroke length under control of an operator, in accordance with the coefiicient of friction of the particular raw material, results in a product of uniform density regardless of the composition of the original mixture fed thereto.

While the stroke adjustment mechanism of the instant invention will be hereinafter illustratively described in conjunction with an apparatus for forming composition board, its applicability to various other types of reciprocating pistons for a wide variety of uses will be readily apparent.

Still other objects of the invention reside in the combinations of elements, arrangements of parts, and features of construction, all as will be more fully pointed out hereinafiter and shown in the accompanying drawings where- FIGURE 1 is an enlarged detail side elevational view of portions of the molding apparatus disclosing the means for controlling the length of the stroke.

FIGURE 2 is a top plan view of the structure of FIG- URE 1, and includes certain other components of the apparatus per se which are not material to the presently claimed invention.

FIGURE 3 is an enlarged detail sectional view taken substantially along the line 33 of FIGURE 2 as viewed 7 in the direction indicated by the arrows.

3,142,185 Patented July 28, 1964 FIGURE 4 is a view similar to FIGURE 3 but showing the component parts in a different position of adjustment.

FIGURE 5 is an enlarged sectional view taken substantially along the line 55 of FIGURE 3 as viewed in the direction indicated by the arrows; and

FIGURE 6 is a sectional view taken substantially along the line 66 of FIGURE 1 as viewed in the direction indicated by the arrows.

Similar reference characters refer to similar parts throughout the several views of the drawing.

Briefly summarized, the apparatus of my above-mentioned co-pending application consists of a base frame 36 which has mounted thereon a lower mold 54 provided with a series of parallel mold grooves 74 and an upper mold 95 with a limited space therebetween into which a piston generally indicated at 66, is intermittently projected, by means to be more fully described hereinafter, the piston being provided with a plurality of spaced apart parallel perpendicularly depending legs integrally secured thereto, and adapted to engage in the lower mold grooves.

A slide bearing 47 is grooved to receive a plurality of slide blocks 52, each of which is provided with a plurality of spaced cars 65, which extend rearwardly from an upstanding transverse bar 64. The mold piston 66 includes a generally rectangular body 67 engaging the upper surface of slide block 52 forwardly of the transverse bar 64 and has a generally horizontal flat panel 69 provided with the depending legs 76 for engagement between the upper and lower molds 95 and 54.

In order to effect reciprocation of the piston 66, a link arm has its forward end positioned between each pair of ears 65 and is pivotally secured therein by means of a stub shaft 76. A plurality of link arms 75 are arranged in spaced parallel rearwardly extending pairs with each pair engaging on opposite sides of a second pair of links 77. The links 77 and link arms 75 are pivotally connected to the upper end of a connecting rod 44 by means of transversely extending pivot pins 78.

A stirrup 79 is secured between upstanding frame members 89 by means of pivot pins 81, while links 77 have the ends thereof opposite pivot pins 78 secured to the stirrup 79 by means of a pivot pin 32.

Stirrup 79 is provided with an upstanding pair of laterally spaced ears 83 between which extends a centrally squared shaft 84 which engages in a generally rectangular horizontal slot 85 and a transversely extending control bar 86. Control bar 86 is mounted on a plurality of vertically extending control rods 86a and a vertically extending control screw 87. The screw 87 is moved vertically by means of a nut 88 doweled to a worm gear 88a, suitable thrust bearings (not shown) being provided at top and bottom, Worm gear 88a being driven by a worm 89 mounted on a shaft 89a and controlled by means of a manually operable hand wheel 90. The assembly operates between top and bottom bearing surfaces 88b within the frame.

Obviously, vertical swinging movement of the stirrup 79 about its pivot 81 changes the effective throw of the connecting rod 44 by bodily moving the link 77 and the link arm 75 longitudinally.

An indicator scale 91 is mounted on the top a of frame member 80 and an indicator pointer 92 is secured to the upper end of the screw 87, cooperating with the scale 91 to indicate the relative adjusted position of the screw 87 so as to permit the accurate adjustment of the throw of the links 75 and 77 Connecting rods 44 are driven by crank throws 43 0 comprising portions of a drive shaft 38 which is rotated From the foregoing the operation of the device should now be readily apparent. The distance between the axis of pivot pin 81 and the axis of pivot pin 82 is identical to the distance between the axis of pivot pin 82 and the axis of pivot pin 78 so that the link 77 can swing about pivot pin 82 to a point where the pivot pin 78 becomes axially aligned with the pivot pin 81. The alignment of the pivot pin 78 and 81 occurs with the connecting rod 44 in its uppermost position and with the mold piston 66 in its rearinost position. By swinging the stirrup 79 downwardly from the position illustrated in FIGURES 1 and 3 to the position illustrated in FIGURE 4, the link 77 and the link arm 75 are moved forwardly so that the stroke of the mold piston is increased. However, regardless of the position of the stirrup 79, the mold piston 66 will be withdrawn to the same beginning position on each revolution of the shaft 38 since the uppermost position of the connecting rod 44 will always cause the pivot pin 78 to become aligned with the pivot pin 81. With this structure, the actual length of the stroke of the mold piston 66 can be effectively changed by manipulation of the hand wheel 90 While the apparatus is in full operation.

It will thus be seen that there is herein provided an improved mechanism for varying the stroke of a piston, which accomplishes all the objects of this invention, and others, including many advantages of great practical utility and commercial importance.

As many embodiments may be made of this invention concept, and as many modifications may be made in the embodiment hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative, and not in a limiting sense.

I claim:

1. A system for driving a block with progressively increasing force repetitively from the same return point to an end point which is se.ectively variable which comprises:

(a) a frame for supporting said block for linear sliding movement away from said return point;

(b) a first link having one end pivotally secured to said block;

() a crankshaft journalled in said frame;

(d) a connecting rod having one end journalled in said crankshaft;

(e) a first pivot means coupling the free ends of said first link and said connecting rod;

(f) a second pivot means selectively movable along an are having as its center the same axial location as said first pivot means when said block is at said return point, and;

(g) a second link secured at its ends to said first pivot means and said second pivot means, respectively.

2. A system for driving a block with progressively increasing force repetitively from the same return point to an end point which is selectively variable which comprises:

(a) a frame for supporting said block for linear sliding movement away from said return point;

(b) a first link having one end pivotally secured to said block;

(c) a crankshaft journalled in said frame;

(d) a connecting rod having one end journalled in said crankshaft;

(e) a first pivot means coupling the free ends of said first link and said connecting rod;

(1) a stirrup having a second pivot means at one end thereof and pivotally mounted at the same axial location as said first pivot means when said block is at said return point;

(g) a second link secured at its ends to said first pivot means and said second pivot means, respectively, and

(/1) means for selectively adjusting the rotational position of said stirrup about said axial location to vary the length of travel of said block.

3. A system for repetitively applying a driving force to a wide material compressing plunger with the force a maximum at the end of each stroke where the stroke is of variable length and always begins at a fixed return point which comprises:

(a) a frame for supporting said plunger for slide movement in the direction of the face of said plunger from a fixed return point;

([2) a crankshaft journalled in said frame;

(0) a pair of connecting rods secured at the driven ends thereof to throws at spaced points on said crankshaft and at identical angular positions;

((1) at least a pair of drive links pivotally connected at the drive ends thereof to spaced points along the back of said plunger;

(2) a first pair of spaced pivot means interconnecting the drive ends of said connecting rods and the driven ends of said drive links in two symmetrical pivot arrays;

(f) stirrup means having at least a pair of stirrup links and pivoted on said frame along a line passing through the axes of said spaced pivot means when said plunger is at said return point;

(g) at least a pair of control links each pivotally con nected at one end thereof to one of said stirrup links and at the other end thereof to one of said pivot means in symmetry with the connecting rod and the drive link connected thereto with the lengths of said control links being equal to the length of said stirrup links; and

(/1) means for simultaneously adjusting the angular position of said stirrup means to reposition the points of connection between said control links and said stirrup links for control of the length of the stroke of said plunger.

References Cited in the file of this patent UNITED STATES PATENTS 2,666,392 Martin Jan. 19, 1954 2,909,163 Biermann Oct. 20, 1959 2,972,894 Bennett Feb. 28, 1961 FOREIGN PATENTS 104,201 Great Britain Feb. 22, 1917 

1. A SYSTEM FOR DRIVING A BLOCK WITH PROGRESSIVELY INCREASING FORCE REPETITIVELY FROM THE SAME RETURN POINT TO AN END POINT WHICH IS SELECTIVELY VARIABLE WHICH COMPRISES: (A) A FRAME FOR SUPPORTING SAID BLOCK FOR LINEAR SLIDING MOVEMENT AWAY FROM SAID RETURN POINT; (B) A FIRST LINK HAVING ONE END PIVOTALLY SECURED TO SAID BLOCK; (C) A CRANKSHAFT JOURNALLED IN SAID FRAME; (D) A CONNECTING ROD HAVING ONE END JOURNALLED IN SAID CRANKSHAFT; 